1. Field of Invention
The present invention relates to an Internet protocol (IP) address operation, and more particularly to a method of operating an IP address that allocates, creates, and processes an interface identifier (ID) in an IP address area, and a subnet system using the same.
2. Description of the Prior Art
Generally, Internet is serviced based on an IPv4 address. Since the IPv4 uses 32 bits address space, logically, it can provide 42 hundred million address spaces. However, the allocation of IPv4 address is done in class unit so that the number of actually usable addresses is smaller than the logical one, which may result in a serious lack of the number of the available addresses when used in home network, ALL-IP, and other networks and devices in the future.
To solve the above problem, an IPv6 address system has been proposed. The IPv6 address uses 128 bits address space, in which the higher order 64 bits are comprised of subnet prefix information, and the lower order 64 bits of an interface identifier (ID).
FIG. 1 illustrates a general IPv6 aggregable global unicast address format. In FIG. 1, higher order 64 bits information is allocated as subnet prefix information in accordance with Internet communication network management rule, and lower order 64 bits information is automatically created as an Interface ID by the use of identifier information provided in a network device.
In FIG. 1, the higher order 64 bits space is divided into multi areas for hierarchical allocation. The 64 bits rows as hierarchically allocated express a subnet prefix and form a complete global unicast address in combination with the Interface ID of the lower 64 bits area.
As illustrated in FIG. 1, the subnet prefix includes 3 bits Format Prefix (FP), 13 bits top level aggregation (TLA) ID, 8 bits REServed for future use (RES), 24 bits Next Level Aggregation (NLA) ID, and 16 bits Site Level Aggregation (SLA) ID. If a value of FP is ‘001’, for example, it indicates one for aggregable global unicast address.
The Interface ID follows an EUI-64 format by the recommendation of the Internet Engineering Task Force, and the Interface ID created following such format is ensured to be a unique Interface ID for a device in a global area or a local area.
As illustrated in FIG. 2, an Interface ID with a format of EUI-64 is comprised of 24 bits Company ID and 40 bits Extension ID, and 128 bits address in combination of the corresponding Interface ID and subnet prefix interface information in the higher order 64 bits is a unique one as a global unicast address.
As described above, since the conventional IPv6 address system is comprised of 64 bits as subnet prefix information and 64 bits as Interface ID, the maximum number of the IPv6 addresses allocatable to a subnet and the number of the device having simultaneous access thereto can be 264, respectively. In this case, a gateway managing one subnet should have 264 routing information, which is a great amount of information. Accordingly, a large amount of memory was required for simultaneous routing, and this caused a delay during matching of routing information.